LS - 1st and 2nd Gen (1990-2000) Discussion topics related to the 1990 - 2000 Lexus LS400

major coolant leak

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Old 07-01-13, 05:37 PM
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Willmkent
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Default major coolant leak

so, a buddy of mine replaced my neighbors timing belt and water pump and now hes leaking coolant completely until the reservoir is empty... my buddy wont be home for a while and was just wondering if anyone else ever experienced this.

he used factory sealant to re seal the water pump....
Old 07-01-13, 05:56 PM
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timmy0tool
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what year car are we talking about? where is the leak coming from? if sealant was used, there is a time frame as to when to apply, set, tighten, and dry depending on what product was used. what sealant brand was used? was the water pump torqued down in sequence (star pattern)? radiator? lots of places can show a coolant leak.
Old 07-01-13, 06:34 PM
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PureDrifter
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he didn't seal it right, needs to get redone by someone who knows what they're doing.
Old 07-04-13, 04:48 AM
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Lexinky
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No sealant is necessarry on the water pump. I used the metal gasket that came with the Aisin water pump in kit part # TKT-010 and torqued it to the specs with no sealant. I have done this on several Toyotas over the last 10 years and have had no issues with leaks. But the engine surface must be perfectly clean before installing.

Sealant can be used, and alot of people get worried about leaks so they do use it, BUT it has to be rated for use with antifreeze and done correctly. My guess is that a type of sealant that was not compatable was used and it did fine for a week or so but then started leaking ( the sealant dissolved). If the leak is at the water pump it will need to be disassembled and at minimum the belt needs replaced because the antifreeze has soaked the belt (not good). If it were me I'd do the entire job over again, replacing everything.

Last edited by Lexinky; 07-04-13 at 05:24 AM.
Old 07-04-13, 01:32 PM
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Willmkent
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Default Coolant leak problem

Hey guys,

So my neighbor and I have been working on his 1995 LS400 and we had a buddy help us out of a timing belt change and a water pump install.

We did everything to spec hoever there was one o-ring that we did not replace which was on the thermostat i believe....

anyways, now the car is leaking coolant bad on a regular basis and we narrowed down where most of it was coming from.



its seeping from this small hole where the transmission is.... Cannot figure out where it would come from to get there,

anyone ever experience this?
Old 07-04-13, 02:01 PM
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LScowboyLS
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heater hose and heater control valve and heater core are in that area, as is A/C evaporator

are you sure it is coolant and not just water? - what is the color?
Old 07-04-13, 02:48 PM
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Willmkent
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its coolant for sure, its like a light lime color. we have been filling the reservoir and watching it leak
Old 07-04-13, 03:59 PM
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LScowboyLS
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Originally Posted by Willmkent
its coolant for sure, its like a light lime color. we have been filling the reservoir and watching it leak
well then it is not A/C evaporator!

those heater related items are the only things coolant related that are as far back as the transmission

make sure it is not leaking from somewhere up front and just running back there
Old 07-04-13, 05:54 PM
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randal
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Wait...there was one O-ring that you did not install or did you mean that you did not replace with a new one(used the old one)? Was any O-ring re-used or left out of either the pump or thermostat?
Old 07-04-13, 07:15 PM
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Willmkent
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it was just not replaced with a new one. now I cannot remember, I wasnt there when that part was reinstalled, but i was under the impression that there was an O-ring that wasnt replaced with new....

where would the coolant be coming from if it is coming through that small channel in the trans
Old 07-04-13, 09:49 PM
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LScowboyLS
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another possibility (unrelated to the timing belt/water pump change) is that this is the exact place where a rear side freeze plug would leak from, if it became corroded and began to leak from age/cooling system lax maintenance.
Old 07-04-13, 10:46 PM
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aomdedude1
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I have a very similar problem. I almost soiled my pants today when I took the flywheel inspection plate (black plate in your picture) off and coolant leaked out.

...but not really though, because I know where my leak is emanating from.

The coolant will leak down the back of the engine and find its way into the flywheel inspection area.

I rented a pressure test kit from pep-boys for free, and did a pressure test on my system.

I discoed a leak in the rear coolant bypass pipe. (part 16356 in this diagram)

What happened was that the part where coolant goes from the pipe to a hose which leads to the heater core some how separated. When I found the leak, I plugged both ends of the hose and bypass pipe with my fingers and had a partner pump the pressure test kit and it ended up passing the test.

(full 15 lbs pressure do not exceed this by too much)


So anyway, what I am saying is do a pressure test. Rent the tool from an autozone or peopboys and it should be easy to find your leak hopefully.

There are quite a few coolant hoses in the rear area of the engine so don't be surprised if you are simply leaking from a hose.
Old 07-04-13, 11:07 PM
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LScowboyLS
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Originally Posted by aomdedude1
I have a very similar problem. I almost soiled my pants today when I took the flywheel inspection plate (black plate in your picture) off and coolant leaked out.

...but not really though, because I know where my leak is emanating from.

The coolant will leak down the back of the engine and find its way into the flywheel inspection area.

I rented a pressure test kit from pep-boys for free, and did a pressure test on my system.

I discoed a leak in the rear coolant bypass pipe. (part 16356 in this diagram)

What happened was that the part where coolant goes from the pipe to a hose which leads to the heater core some how separated. When I found the leak, I plugged both ends of the hose and bypass pipe with my fingers and had a partner pump the pressure test kit and it ended up passing the test.

(full 15 lbs pressure do not exceed this by too much)


So anyway, what I am saying is do a pressure test. Rent the tool from an autozone or peopboys and it should be easy to find your leak hopefully.

There are quite a few coolant hoses in the rear area of the engine so don't be surprised if you are simply leaking from a hose.
this sounds likely to the the problem on that 95 model in the original post! - good diagnosis

welcome to Club Lexus - what a great first post!
Old 07-05-13, 06:13 AM
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Willmkent
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Yes thank you very much, I'm going to relay the information and give this a try!
Old 07-05-13, 06:40 PM
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aomdedude1
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Originally Posted by Willmkent
Yes thank you very much, I'm going to relay the information and give this a try!
Hope it goes well.

..and thank you LScowboy.


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